Are you interested in taking pictures underwater with your Xperia Z? Well I have some good and bad news for you.
The Bad News
This phone is designed to be water resistant, but you cannot touch the screen while you are underwater. This means you cannot at all take photos under water. Why Touch Screen Functionality Doesn’t Work Under Water? Is it Sony’s manufacturing fault? NO! This is not a fault of Sony, it’s because water conducts electricity.
The Good News
An alternative method can be to install any other camera app from app store like Camera 360 that lets you set volume buttons as a Camera hardware button to take photos. Some Dev’s do make mods that allow you to use volume buttons as camera triggers to take pictures, instead of touching the screen. Read below article. http://www.xda-developers.com/android/give-your-sony-xperia-z-a-physical-camera-button/